There might be a chance that my home town where I still reside would´ve been either underwater or just above it and in very southern tip of that map. Currently this town is about 100 meters above sea level. I was also thinking about the continents that might make a "wave effect" that they would be higher up on one side and lower in the other, which would be extremely slow going or in some certain intervals and that would render some theories useless, if that sort of thing is even possible, why not though.

Most of the Chinese characters on the map are transliterations of the locations, so I think maybe there are not much new information to tell you.

The search results of this map on the Chinese search engine do include something interesting, a Chinese researcher( he has a English blog) says the map is created at about 1430 AD by Zhenghe's fleet, and is a proof of Zhenghe came to America before Columbus, because this map is more accurate than the later Western maps, for example in this Chinese blog.